Elevator control system



J. E. MAGEE ELEVATOR CONTROL SYSTEM Filed July 11, 1960 3,073,962 ELEVATOR CONTRL SY STEM John E. Magee, Greenburgh, N.Y. (191 Forest Blvd., Ardsley, NX.) Filed `luly 11, 1966, Ser. No. 41,853 Claims. (Cl. 137-29) This invention relates to dispatching and control systems for a plurality of elevators operating as a group.

It is desirable in present day elevator installations to control the operation of a group of elevators in such manner as to provide distributed service of these cars in the group to the various floors of a building. It may further be desirable to vary distribution of the cars relative to a specific floor or iloors. It is known in this art to vary such distribution of cars based on the number of cars in service at any speciiic time and to control their distribution based on actual registered demand for service.

ln my prior copending application, Serial No. 829,419 entitled Predicted Stop Demand and tiled July 24, 1959 [now Patent No. 2,944,634] there is disclosed a system in which a predicted demand factor is established for each direction of travel from each landing of a building. This predicted demand factor is determined in accordance with the service characteristics of the tenancy of that landing and the type of service required by such tenancy and is utilized as part of the total demand to eicct dispatching of the cars. Registered landing calls are also a part of the total demand. The predicted demand and registered demand are totalized up to the position of the car next preceding the one selected as next to be dispatched. When such totalized demand reaches a predetermined amount for the particular installation, the Selected car is dispatched. In this manner, the system tends to serve each landing with regularity according to its anticipated needs, which regularity is automatically modified by the registration of demand at the landings. The removal or addition of a car from group operation automatically changes the amount of totaliz'ed demand utilized to effect the dispatching of a car.

The present invention relates to improvements in the control systems disclosed in the abovefidentied application. In the system disclosed in said application, in the absence of registered demand, or in Some cases, when one or more landing calls are registered, depending upon the number of demand units allocated to a registered demand, the succeeding car is dispatched when the preceding car reaches a predetermined landing such as a terminal or dispatching landing or a landing one or more floors ahead of the terminal landing. However, such system does not take into account the time taken for the preceding car to travel from a terminal landing to such predetermined landing, and therefore, the succeeding car may not vbe dispatched as promptly as may be desirable under the circumstances, or the succeeding car may be dispatched before it is necessary to do so. For example, if the preceding car makes several stops in going from one terminal landing to the opposite terminal landing and if there are no registered landing calls, or an insuiiicient number of landing calls, after the preceding ca r there will be a relatively long period of time between the time that the landings are serviced by the preceding car and the time that such landings are serviced by a succeeding car. On the other hand, if the preceding car travels from one terminal to the other without stopping, the succeeding car will be dispatched before service is required at the floor passed by the preceding car whether or not any landing calls have been registered after the preceding car has passed the several floors.

The above described difficulties are encountered because a preset number of demand units are assigned tol the various iloors dependent upon the predicted demand for these oors. In accordance with the present invention, a repeat service demand factor is initiated by passage or departure of a car from each landing serviced by each car. The magnitude of this factor is caused to increase With time, commensurate with the need for repeat' l service to that landing by that car or any other car of a group of cars. At any point in time the repeat service demand factors are totalizcd for all landings between a.

. limit effect of such registered landing demand to that forl oors between the terminal and the nearest previously departed car. Also, it may be advisable to limit effect of registered demand in the selected car to one or two callsy to avoid a multiplicity of falsely registered car calls unduly affecting premature dispatch of the car.

In other respects, the operation of the system of th invention may be the same as the system described in my above-identified copending application, that is, if desired the circuits for controlling the dispatching of cars by the car calls and landing calls may be included so that the dispatching of cars is controlled by the car and landing calls as Well. Similarly, the circuits for reading the demand ahead of the previously dispatched car as well as the other circuits, except for the predicted demandl resistors, may be included.

It is one object of the invention to provide a dispatching and control system for a group of elevators in which the response of the cars to demands for service at the' landings is on an individual car basis in accordance with the repeat service demand to which each car is subject.

In carrying out the invention according to the preferred embodiment, the repeat service demand factor for each direction of travel from each landing of a building is,

initiated by departure of a car from such landing regardless of whether or not such departure followed a stop at such landing. This repeat service demand factor increases with time from its moment of initiation until it reaches substantially its assigned value, unless erased by the availability of a succeeding car disposed to provide service at such landing. The repeat service demand and actual registered demands are totalized up to the position of the car next preceding the one selected as next to be dispatched. When such totalized demand reaches a predetermined amount for the particular installation, the selected car is dispatched. In this manner, the system tends to distribute service according to expired times since certain landings received prior service supplemented or modied by the registered demand at such landings. The removal of a car from group operation or addition of a car to groupoperation automatically changes the amount venvases 3 of totalized demand utilized to elect the dispatching of a car.

Other objects and advantages of the invention will be apparent from the following detailed description of the preferred embodiment thereof, which description should be considered in conjunction with the accompanying drawing in which:

FIG. 1 is a simplified schematic wiring diagram corresponding to FIG. 4 of my copcnding application aboveidentified and illustrates the modifications of the apparatus shown in my copending application required for the system of the present invention.

As pointed out above, except for the modifications in the circuits and operations required for the present invention,- the operation of the elevator control system of the present invention may be the same as the operation of the elevator control system set forth 'in said copending application and the specification and drawings of -said copending application are incorporated herein by reference. It should be noted here that the' only changes required in the circuits illustrated in the drawings of said .copending application are changes in the circuits illustrated in FIG. 4 of said application and such changes are illustrated in FIG. 1 ofthe drawing of the present application.

In general, the changes consist of the replacement of the resistors lPUR through 16PUR and resistor ZPDR through 17PDR shown in FIG. 4 of said application by relay controlled charging, discharging and isolating circuits comprising the following:

ResistorsllXUR-MXUR and ZXDRfUXDR lYUR-IGYUR and 2YDR-,17YDR l lZUR-lZUR and 2ZDR-.17ZDR Contacts- '.2PID3-'17PID3 .and 1PIU3-16PIU3 ZPID4-17PID4 and 1PIU4-16PIU4 Rectifiers--RZUl-RZUIG and RZD2RZD17 Capacitors-QZUl-QZUl and QZD2-QZD17 'The remaining elements shown in FIG. 1 have the same functions and purposes as the corresponding elements` Contacts of down direction switch DN Contacts of up direction switch U'P Brushes BPU and BPD Stationary contacts PU and PD Zener diodes ZDD and ZDU Manually operable switches KSU The letters X and Y followed by numerals indicate that the leads designated thereby are interconnected, leads X1 being interconnected with each other, leads Y1 being interconnected with each other, etc.

The invention will be described, for convenience, as a control and dispatching system for a three car group of elevators serving seventeen landings, designated one through seventeen. In the arrangement illustrated the first landing is the lower dispatching landing, and the seventeenth landing is the upper dispatching landing. It will be understood that the principles of the invention are equally applicable to elevator installations having different numbers of landings, different numbers of cars and diffe-rent landings utilized as dispatching landings.

l .Differentiation will be made between the different elevators by appending to the characters, employed to designate the various elements of the system, lower case letters'y 11, b and c, indicative of the different elevators.

The circuits for lsome of the intermediate landings have been omitted, for the sake of brevity, and it is to be understood that the circuits for such intermediate landings are intended to be similar to those illustrated for other intermediate landings. Similarly, the circuits which are individual to each car are shown only for car a, it being understood that like circuits are provided for cars b and c.

As explained in said copending application, letters are employed as reference characters to identify coils of electromagnetic switches and, with reference numerals appended thereto, to identify the contacts of the switches to differentiate between different sets of contacts on he same switch, all contacts being shown for the unoperated condition of the switches. A numeral prefix included in a reference character indicates the landing with which the` element designated by the reference character is associated.

Referring to FIG. 1, the demand totalizer circuits for up dispatching include a triode tube PTU, which, when the. demand islow, conducts insuicient current'to operate the summation up demand switch PDU which operates the dispatchingcircuits. The amount of current ow through the tube is controlled by the potential applied to the grid of the tube. This` in turn is determined by the position of adjustable tapy T1 on resistor PDURl which fixes the total demand required for applying a value of positive potential on the grid sufiicient to cause the tube to conduct the amount of current required-to operate the switch. PDU. Similarly, demand totalizer circuits for down dispatching include the triode tube PTD andan adjustable tap T1 on the resistor PDDRl, the position of which determines the total demand required for applying a-Value of positive potential on the grid of the tube PTD sufficient to cause the tube to conduct current in an amount sufficient to operate the .switch PDD.

Asexplained in my copending application, switches PDU vand PDD act to initiate dispatching of selected cars in the manner set forth in said application. The total demand for causing dispatching of a selected car under conditions where one car of the group is removed from group operation is determined by the positions of the adinstable taps T2-T4 on resistors PDURI and PDDRI in the. manner explained in said application. Respective pairs of contacts CSla-c and CS5ac are caused to close when manually operable switches are operated Vto select thecar to be Aplaced in service,

Resistors PDURI and PDDRl are connected in parallel respectively with stabilizing capacitors QPU and QPD. @ne end of resistor PDURl is connected through normally closed contacts WBX3a-c of the up dispatch holding switch WBX [not shown herein] to the various demand circuits hereinafter described and one end of the resistor PDDRl is connected through the normally closed contacts WTX1a.-c of the auxiliary down selected car switch WTX [not shown herein] to the various demand circuits hereinafter described.

The demand due to the car calls registered for a car which is selected is totalized in the up demand totalizing circuits by means of car call demand resistor RKBa-c and, in the down demand totalizing circuit, by means of car call demand resistors RCKa-c, the contacts CKBZa-c and CKTla-c being operable respectively by the up selected car, car call switch CKD [not shown herein] and the down selected car, car call switch CKT [not shown herein]. The closing of a contact CKBZa-c or CKTla-c connects one end of the associated resistor to the B+ line.

As explained in said copending application, the operation of a down landing call button causes application of a positive potential to the corresponding lead WD2-17 and operation of an up landing call button causes the application of a positive potential to the corresponding lead WUI-16. i

The repeat service demand circuits comprise a pair of envases contacts of a down car position switch PID [not shown herein] or an up car position switch PEU [not shown herein], a resistor XDR or XUR, a resistor ZDR or ZUR, a resistor YDR or YUR, a capacitor QZD or QZU and a rectifier RZD or RZU. The operation of one of the repeat service demand circuits will be described in detail, it being understood that the other repeat service demand circuits operate similarly.

As shown in the upper left hand portion of FIG. l, the adjustable resistor llXDR is connected in series with the normally closed contact WPIDS and the capacitor QZDl between the B+ lead and the lead B at lower potential. When the contacts MMDB are initially closed the potential at the junction point between these contacts and the capacitor QZDl' will commence to rise at a rate dependent upon the value of the capacitor QZDl and the adjustment of the resistor EXDR. This junction point is also connected through a resistor lZDR and a rectifier RZD'7 to the lead 2d?, to which the landing call button circuit for the seventeenth landing is also connected through the lead WDi', the rectitier RWDE? and the adjustable resistor ll'RDl. As long as the potential at the junction point between the contacts UPDS and the capacitor QZD17 is less than the potential of the line ZtiZ the potential at this point will have no effect on the up demand totalizing circuit. However, if the contacts WBXSa-c, ZPlUl-lit and Ii7PlDl are closed and the potential at said junction point exceeds the potential on the line 202, the potential on the grid of the tube PTU will rise by an amount dependent upon the relative values of the resistor lZDR and the portion of the resistor PDURl in circuit between the Contact WBXSC and the B lead. Accordingly, the amount of time required for the voltage at the junction point of the contact li'PlDS with the capacitor QZD17 to reach a predetermined demand level may be adjusted by adjusting the resistor l'XDa and the effect of the demand may be adjusted by adjusting the value of the resistor HZDR.

The contacts l'PlD are opened when a car a is at the seventeenth landing or terminal, and are closed when the car a departs from the seventeenth landing. Similarly, the contacts lPIDd are closed when the car a is at the seventeenth landing and are opened when the car a departs from the seventeenth landing. When the car a is at the seventeenth landing, the capacitor QZDl' discharges rapidly through the closed contacts lPiDd and the resistor ltYDR having a relatively low value compared to the value of the resistor lXDR. Thus, each time that a car arrives at a landing it discharges the capacitor of the repeat service demand circuit associated with such landing and such capacitor commences to charge after the car has left the landing.

Similarly, the effect of a landing call demand on the tube PTU may be adjusted by adjusting a resistor RDR or RUR and the effect of the car call demand may be adjusted by adjusting a resistor RKB or RCK, the magnitude of such resistors in relation to the magnitude of the in circuit portion of the resistors PDURll or PDDR detemining the magnitude of the potential applied to the grid of the tube PTU or the grid of the tube PTD due to one of these demands. In this respect the operation of the registered demand circuit shown in FlG. l is the same as for the corresponding demand circuits described in said copending application.

However, unlike `the predicted demand circuits described in said copending application, the effect of the repeat service demand circuits of the present invention is variable with time and is dependent upon the length of time since the landing was last passed or serviced by a car. Furthermore, by progressively altering the elrect of the repeat service demand circuits and for the registered demand as the distance from a terminal landing is increased, the time taken for a car to travel from a terminal landing to a more remote lioor may be taken into account so as to improve the service to such more remote landings.

It will be apparent from the foregoing that when the potent-al on the grid of the tube PTU and PTD is raised suilciently by means of the potentials applied to the corresponding resistors PDURl and PDDRl by the car call circuits, the landing call circuits and the repeat service demand circuits to cause the tube PTU or PTD to conduct enough current to cause operation of the associated electromagnetic switch PDU or PDD, the next succeeding car selected for dispatching will be dispatched in the manner described in said copending application. lt is to be understood that the total demand required for dispatching a car, the weight or effect established for the individual rei eat service demand and for the car call and landing call registered demand may vary in accordance with the characteristics of each particular installation. Furthermore, they may be readjusted in a particular installation as experience and changes in tenancy dictate. Also, if it is desired for a particular installation, the repeat service demand for a given direction of travel may be given more weight in establishing a demand for dispatching a selected car in that direction than the weight given to the repeat service demand for dispatching a selected car in the opposite direction. For example, when an up travelling car stops in answer to a landing call, the entering passenger usually registers a car call for another landing requiring that car to make a second stop before it reaches the upper dispatching landing. When a down travelling car stops in answer to landing calls, the entering passengers in many instances wish to travel directly to the lower dispatching landing. lt `therefore may be desirable to establish for the landings a greater repeat service demand in the up direction than in the down direction.

Let it be assumed that for the purposes of a particular installation, the car call and landing call demand circuits described above are omitted and that the dispatching of a selected car is initiated by the repeat service demand. Let it be assumed also that the repeat service demand may be expressed in units of basic demand in the manner described in said copending application and that the units of repeat service demand in the up direction are allocated as follows:

Table A Up Repeat Service Demand Units 3 sec. 6 sec. 9 sec. 12 sec. 15 sec.

In the foregoing Table A, it is assumed that the maximum number of demand units is reached at each oor in 15 seconds. However, if desired, the demand units may reach their maximum Values at different times at different doors.

Next assume that the total repeat service demand for dispatching a selected car is established as fifteen demand units for each direction. ln other words, with three cars in group operation, adjustable taps T1 are positioned on resistors PDURI and PDDRI so as to prevent each of the tubes PTU and PTD from conducting suticient current to initiate dispatching of a selected car until the totalized demand to which the selected car for the corresponding direction of dispatching is subject reaches aptotal of fteen demand units. For each direction of travel, this occurs when the potentials supplied by the car call circuits, the landing call circuits and the repeat service demand circuits, cause the potentials on the grids of the tubes PTU or PTD to reach values which will cause operation of the associated switch PDU or PDD.

Assume that cars a, b and c are at the lower dispatching landing, set for upward travel and are put into group operation in the order a, b and c in the manner described spaanse in said copending application. In the absence of car calls registered in selected car a and of landing calls in registration, there will be suicient service demand in the system, under the assumed conditions, and assuming that the repeat service demand circuits have previously been energized for about fifteen seconds to cause car a to be dispatched upward immediately. Such demand is due solely to the summation of the repeat service up demand established at the landings and is totalized as follows: a plurality of circuits is established through resistor PDURI, one such circuit extending from line B-lthrough resistor 17XDR, contacts 17PID3, resistor l'ZDR, rectifier RZD17, con-tacts 17PID1 and 16PIU1 through ZPlUl, contacts WBXSrz-c and resistor PDURl to line B similar circuits being completed through resistor PDURl from line B+ through repeat service up demand resistors 16XUR through ZXUR and their associated circuits, representing the repeat service demand from the sixteenth through the second landings respectively. Therefore, in approximately tifteen seconds the total number of de rmand units is as follows:

Since it has been assumed that adjustable tap Ti is so positioned on resistor PDUR that current flowing through this resistor due to rteen demand units is sufiicient to dispatch car a, a positive potential is applied to the grid of tube PTU with respect to its cathode of high enough value to lcause tube PTU to conduct current through the coil of summation up demand switch PDU of a value to cause this switch to operate.

Through the circuits described in said copending application, car a is dispatched upwardly and causes sequential operatiou of switches PIU and their associated contacts, switches PIU as they operate and release in sequence separate and then engage their respective contacts V2PIU1 through 16PIU1 and ZPIUS through 16PIU3 and, conversely, engage and then separate the contacts PIU4 through l6PIU4 in sequence. As car a starts upward from the lower dispatching landing it opens contacts ZPIUIl, as'describ'ed in said application, thereby isolating the demand circuits ahead of car a from affecting the up dispatching totalizer. Contacts ZPIUS also open and contacts 2P1U4 close discharging capacitor QZUZ. As car a leaves the second landing, switch PIU releases to reclose contacts ZPUl and 2PIU3 and to open contacts 2PIU4, completing a circuit through resistor PDURi, the circuit extending from line B-lthrough resistor XUR, contacts ZPIUS, resistor ZZUR, rectier RZU2, contacts ZPIUI, WBXSa, WBXSb, WBXSc and resistor PDURI to line B. This causes a current to ow through resistor PDURI which increases in magnitude with time to a rate dependent upon the values of ZXUR and QZUZ. Upon continued upward car movement contacts SPIUI open and contacts SPIUS open and contacts 3PIU4 close isolating the demand circuits ahead of car a from the up dispatching totalizer and discharging capacitor QZU3, associated with the third landing. As car a leaves the third landing, switch SPIU releases to reclose contacts SPIUI, inserting the repeat service demand circuit for `the third landing in parallel with the repeat service demand circuit for the second landing in the up totallizing rcircuit, thereby increasing the current ow through res istor PDURL In a similar manner, as car a continues upward, additional repeat service demand circuits are Table C Demand Landing Arrive Departure Units on Departure The values of the demand units in Table C are calculated using the times indicated above and the values of demand units for the various landings set forth in Table A. From the foregoing it will be seen that the up demand units equal approximately fifteen shortly after car a passes the thirteenth floor and hence about thirty-three seconds after car a is dispatched from the lower dispatching landing.

As another example, let it be assumed that car a stops at landings 4, 8 and l2 and that the times are as set forth below, then the approximate up demand units will be:

The values of the demand units are calculated as set forth above in connection with Table C, and it will be apparent that the up demand units will exceed fifteen while car a is at the twelfth oor so that car b will be dispatched from the lower dispatching landing about thirty-six seconds after car a departed therefrom.

Similarly, it may be shown that if car a makes no stops and takes about sixteen seconds to reach the upper terminal or landing seventeen, car b will be dispatched as car a approaches landing seventeen.

lf the landing call and car call demand circuits are included in the system, the dispatching of car b will be affected by the registration of car calls in car b and by the registration of landing calls at landings below the position of car a as it travels to the upper dispatching landing. For example, if car calls are assigned a value of five units for one or more calls and the conditions are those assumed in Table D, and if an up car call is registered in car b before car a reaches the eighth floor, or while there, car b will be dispatched While car a is stopped at the eighth iioor. If an up landing call is assigned three units and is similarly registered behind car a, instead of a car call in car b, it Will cause dispatching of car b in a similar manner and shortly after car a leaves the eighth oor. The registration of more than `one car call in car b under these conditions will not cause earlier dispatching of car b [one or more car calls total live units], but if there are no car calls in car b and two landing calls are registered at the landings behind car a, car b will be dispatched upon registration of the second landing call if car a is approaching the eighth landing or is at the eighth landing or higher. Similarly, one car call registered in car b and a landing call registered at a landing behind car a will cause car b to be dispatched while car a is between the fourth and eighth landings. Other examples of the operation for similar conditions or for other demand unit assignments and requirements will be readily apparent to those skilled in the art.

ln a similar marier, the dispatching of a car in the downward direction may be controlled by assigning selected demand unit values to the repeat service demand circuits for the downward direction and to the down car call and landing call circuits.

lt will be noted from the foregoing description that the dispatching of a succeeding car is not dependent solely upon the registered car and landing calls and the position of the preceding car. Instead, the dispatching of a succeeding car is dependent upon the registered car and landing calls, the position of the preceding car and the time taken by the preceding car to travel between the various landings, and therefore, the system of the present invention, if adjusted in accordance with the principles described above, will vary the dispatching intervals in accordance with the traliic conditions and will tend to provide repeat service at a landing at more nearly equal intervals under Varying traic conditions.

Without further modifications of the circuits described in said copending application, the system of the present invention may have all of the various operational features of the system described in said copending application. However, if desired certain of the operating features described in said copending application may be omitted by omitting the corresponding circuits. For example, if it is desired to eliminate the preordained reversal operation and the dispatching of a car in answer to a call which has been registered for a predetermined length of time, the switches BLT and PHC and their associated circuits and contacts described in said copending application may be omitted. Furthermore, if it is desired to eliminate control of car dispatching by either car calls or landing calls the corresponding demand circuits shown in FIG. l and described above may be omitted.

Having thus described my invention with particular reference to the preferred form thereof and having shown and described certain modiiications, it will be obvious to those skilled in the art to which the invention pertains, after understanding my invention, that various changes and other modications may be made therein without departing from the spirit and scope of my invention, as dened by the claims appended thereto.

What is claimed as new and desired to be secured by Letters Patent is:

l. An elevator dispatching and control system for a plurality of elevator cars serving a plurality of landings, said system comprising service demand means including time variable repeat service demand means for at least one of said served landings and controlled by said cars for establishing a time variable demand for service for the landing for which it is provided, and dispatching control means responsive to said service demand means including said repeat service demand means for causing dispatching of a selected car when the total service demand exceeds a predetermined amount.

2. In an elevator control system for a plurality of elevator cars serving a plurality of landings from a dispatching landing, a plurality of first service demand means, one for each of said plurality of landings except the uppermost landing, including means for establishing a time variable repeat service demand for service in a direction away from said dispatching landing, a plurality or second service demand means, one for each of said plurality of landings, including means for establishing a time variable repeat service demand for service in a direction toward said dispatching landing, and dispatching means controlled by said first and second service demand means for dispatching selected cars from said dispatching landing, said dispatching means dispatching a selected car under conditions where a predetermined amount of service demand is established behind all cars previously dispatched from said dispatching landing. Y

I3'. in an elevator dispatching and control system for a piurality of elevator cars serving a plurality of landings from a dispatching landing, said system comprising, dispatching means for dispatching the cars from said dispatching landing, and selecting means for selecting a car to be dispatched from said dispatching landing, the combination therewith of repeat service demand means for establishing a time variable demand for service for each of said served landings, demand summation means subject to said repeat service demand means for totalizing the demand for repeat service, and circuit control means responsive to said demand summation means for causing said dispatching means to dispatch a selected car when the demand for service to which that car is subject exceeds a predetermined amount.

4. A dispatching and control system for a plurality oi elevator cars serving a plurality of landings from a dispatching landing, said system comprising, means tor selecting one of said cars for dispatching from said dispatching landing, landing call registering means common to said cars for registering demands for service at each of said landings, car call registering means individual to each of said cars for registering demands for service by that car, repeat service demand means for each of said landings common to said cars for establishing a time variable demand for service for that landing, and dispatching means controlled by said registering and repeat service demand means for dispatching from said dispatching landing a car selected by said selecting means under conditions where there exists a predetermined amount of said service demand to which said selected car is subject.

5. A dispatching and control system for a plurality of elevator cars serving a plurality of landings from a dispatching landing, said system comprising, means for selecting said cars for dispatching in a given direction from said dispatching landing, landing call registering means for each of said served landings and common to said cars for registering actual demand for service in said given direction from the landing for which it is provided, repeat service demand means for each of said served landings and common to said cars for establishing a time variable demand for service in said given direction from the landing for which it is provided, demand summation means for totalizing the actual demand registered by said landing call registering means and the repeat service demand established by said repeat service demand means, car position and sensing means responsive to the relative positions and directions of travel of said cars for isolating the registered and repeat service demand ahead of the car next preceding said selected car from being totalized by said demand summation means and for initiating the operation of each repeat service demand means at each landing behind said next preceding car, and dispatching means controlled by said demand summation means for causing a car selected by said selecting means to be dispatched under conditions where at least a predetermined amount of service demand is totalized by said demand summation means.

6. A dispatching and control system for a plurality of elevator cars serving a plurality of landings from a dispatching landing, said system comprising, means for selecting said cars for dispatching in a given direction from said dispatching landing, landing call registering means, one for each of said served landings and common to said cars, for registering actual demands for service from said landings in said given direction, car call registering means for each car, one for each of said served landings, for registering actual demand for service lirom within that car, repeat service demand means for each of said served landings and common to said cars for establishing a time variable demand for service in said given direction from the landing for which it is provided, demand summation means for totalizing the actual service demand in said given direction registered by said landing call registering means, actual service demand registered by said car call registering means for the selected car and the repeat service demand established by said repeat service demand means, car position sensing means responsive to the relative positions and directions of travel of said cars for preventing the service demands registered and established for landings ahead of the car next preceding said selected car from being totalized by said demand summation means and for initiating the operation of each repeat service demand means at each landing behind said next preceding car, and dispatching means controlled by said demand summation means for causing said selected car to be dispatched under conditions where at least a predetermined amount of said service demand is totalized by said demand summation means.

7. A dispatching and control system for a plurality of elevator cars serving a plurality of landings from a dispatching landing, said system comprising, repeat service demand means for each of said served landings and common to said cars for establishing a time variable demand for service in said given direction from the landing for which it is provided, each said repeat service demand means comprising a capacitor and charging and discharging circuits therefor, demand summation means connected to said repeat service demand means for totalizing the repeat service demand in said given direction, car position sensing means responsive to the relative positions and direction of travel of said cars for preventing the repeatr service demands established for landings ahead of the car next preceding said selected car from being totalized by said demand summation means and for-'discharging each said capacitor as a car arrives at a landing and subsequently initiating charging of each said capacitor as a car leaves a landing, and dispatching means controlled by said demand summation means for causing said selected car to be dispatched under predetermined service demand conditions, at least a portion oi said service demand conditions including said repeat service demand.

8. In an elevator control system for a plurality lof elevator cars serving a dispatching landing and a plurality of other landings, means controlled by said cars for measuring the elapsed time since a car was `at one of said other landings and means responsive to said measuring means for controlling the operation of at least one of said oars. 9. In an elevator system for a plurality of elevator cars serving a dispatching landing and a plurality of other landings, means controlled by said oars for measuring the time elapsed since a car departed from one of said other landings and means responsive to said measuring means for controlling Ithe operation of at lease one of said cars.

l0. In Ian elevator system for a plurality of elevator cars serving a dispatching landing and a plurality of other landings, means controlled by a car for measuring the time elapsed since said car departed from each of a plurality of said other landings and means responsive to said measuring means for controlling the dispatching of said cars from said dispatching landing.

1l. In an elevator system having a car serving a dispatching landing and a plurality of other landings, means controlled by said car for measuring the time elapsed since said car departed from one of said other landings and means `responsive to said measuring means for controlling the dispatching of said car from said dispatching landing.

l2. An elevator dispatching and control system for a plurality of elevator cars serving a plurality of landings, said system comprising service `demand means including time variable repeat service demand means for at least one of said landings and controlled by said cars for establishing a time variable demand for ser-vice for the landing for which it is provided, Without the registration of a demand at said last-mentioned landing by an intending passenger, and dispatching control means responsive to said demand means including said repeat service demand means for causing dispatching of a selected car when the total service demand exceeds a predetermined amount.

13. An elevator dispatching and control system for an elevator car serving a plurality of landings, said systern comprising service demand means including time variable repeat service demand means for at least one of said plurality of landin-gs and controlled by said car for establishing a time variable demand for service for the landing for which it is provided without the registration of a demand at said last-mentioned landing by an intending passenger, and dispatching control means responsive to said demand means for `causing dispatching of said car when the total service demand exceeds a predetermined amount.

14. An elevator dispatching and control sytsem for a plurality of elevator cars serving a plurality 'of landings ,from a dispatching landing, said system comprising service demand means including time variable repeat sewi'ce dmeand Ameans for at least one of said plurality of landings and controlled by at least one of said cars for establishing a :time variable demand for service for the landing yfor which it is provided without the registration of a demand at said last-mentioned landing by an intending passenger, and dispatching control means responsive to said `'demand means for causing dispatching of a selected car from said dispatching landing when the total service ldemand exceeds a predetermined amount.

l5. An elevator dispatching and control system for a pluralityv of elevator cairs serving a plurality of landings from a dispatching landing, said system comprising service demand means including time variable repeat service demand means for said plurality of landings and controlled by said cars for establishing a time variable demand for service for said plurality of landings without the registration of a demand at said plurality of landings by an intending passenger, and dispatching control means responsive to said demand means for causing dispatching of a selected car from said ydispatching landing when the total service demand exceeds a predetermined amount.

References Cited in the tile of this patent UNITED STATES PATENTS 

5. A DISPATCHING AND CONTROL SYSTEM FOR A PLURALITY OF ELEVATOR CARS SERVING A PLURALITY OF LANDINGS FROM A DISPATCHING LANDING, SAID SYSTEM COMPRISING, MEANS FOR SELECTING SAID CARS FOR DISPATCHING IN A GIVEN DIRECTION FROM SAID DISPATCHING LANDING, LANDING CALL REGISTERING MEANS FOR EACH OF SAID SERVED LANDINGS AND COMMON TO SAID CARS FOR REGISTERING ACTUAL DEMAND FOR SERVICE IN SAID GIVEN DIRECTION FROM THE LANDING FOR WHICH IT IS PROVIDED, REPEAT SERVICE DEMAND MEANS FOR EACH OF SAID SERVED LANDINGS AND COMMON TO SAID CARS FOR ESTABLISHING A TIME VARIABLE DEMAND FOR SERVICE IN SAID GIVEN DIRECTION FROM THE LANDING FOR WHICH IT IS PROVIDED, DEMAND SUMMATION MEANS FOR TOTALIZING THE ACTUAL DEMAND REGISTERED BY SAID LANDING CALL REGISTERING MEANS AND THE REPEAT SERVICE DEMAND ESTABLISHED BY SAID REPEAT SERVICE DEMAN MEANS, CAR POSITION AND SENSING MEANS RESPONSIVE TO THE RELATIVE POSITIONS AND DIRECTIONS OF TRAVEL OF SAID CARS FOR ISOLATING THE REGISTERED AND REPEAT SERVICE DEMAND AHEAD OF THE CAR NEXT PRECEDING SAID SELECTED CAR FROM BEING TOTALIZED BY SAID DEMAND SUMMATION MEANS AND FOR INITIATING THE OPERATION OF EACH REPEAT SERVICE DEMAND MEANS AT EACH LANDING BEHIND SAID NEXT PRECEDING CAR, AND DISPATCHING MEANS CONTROLLED BY SAID DEMAND SUMMATION MEANS FOR CAUSING A CAR SELECTED BY SAID SELECTING MEANS TO BE DISPATCHED UNDER CONDITIONS WHERE AT LEAST A PREDETERMINED AMOUNT OF SERVICE DEMAND IS TOTALIZED BY SAID DEMAND SUMMATION MEANS. 